JP2015005604A - Solar cell module, and photovoltaic power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module and a photovoltaic power generation device, that can have high power generation efficiency.SOLUTION: A solar cell module includes: a light-condensing plate which has a light incidence surface and a light emission surface having smaller area than the light incidence surface, and absorbs part of external light made incident from the light incidence surface by one or a plurality of optical functional materials, converts the light into light different from the light absorbed by the one or plurality of optical functional materials, and emits the light from the light emission surface; a solar cell element which receives the light emitted from the light emission surface of the light-condensing plate; and a wavelength conversion body which absorbs light, not absorbed by any of the one or plurality of optical functional materials, of the light made incident on the light incidence surface, converts the light into light to be absorbed by one of the one or plurality of optical functional materials, and emits the light.

Description

  The present invention relates to a solar cell module and a solar power generation device.

  A solar energy converter described in Patent Document 1 is known as a solar power generation device that generates power by installing solar cells on the end face of a light collector and making light propagated through the light collector enter the solar cells. It has been. This solar energy converter generates electricity by causing a phosphor to emit light by sunlight incident on the light collector and propagating the fluorescence emitted from the phosphor to solar cells installed on the end face of the light collector. Yes.

  On the other hand, in Patent Document 2 and Patent Document 3, a plurality of phosphors are dispersed inside the light guide, and light incident on the light guide is converted into light having higher spectral sensitivity in the solar cell element than the light. However, a configuration for entering the solar cell element is disclosed.

JP 58-49860 A International Publication No. 2012/63651 International Publication No. 2012/115248

  By the way, a sunlight spectrum has a wavelength range of 280 nm to 4000 nm. In Patent Documents 1 to 3, the phosphor can absorb light in the wavelength range of 300 nm to 600 nm in the sunlight spectrum, but cannot absorb light in the wavelength range exceeding 600 nm. Therefore, light in a wavelength region exceeding 600 nm in the sunlight spectrum is transmitted through the light guide and does not contribute to power generation. Therefore, Patent Documents 1 to 3 cannot achieve high power generation efficiency.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a solar cell module and a solar power generation device capable of obtaining high power generation efficiency.

In order to achieve the above object, the present invention employs the following means.
(1) That is, the solar cell module according to the first aspect of the present invention has a light incident surface and a light exit surface having an area smaller than that of the light incident surface. A condensing plate that absorbs part of light by one or more optical functional materials, converts the light into light different from the light absorbed by the one or plural optical functional materials, and emits the light from the light exit surface; A solar cell element that receives light emitted from the light exit surface of the light plate, and absorbs light that has not been absorbed by any of the one or more optical functional materials among light incident on the light incident surface; And a wavelength converter that converts the light to be absorbed by any one of the one or more optical functional materials and emits the light.

  (2) In the solar cell module according to (1), the wavelength converter may be disposed on the surface of the light collector plate opposite to the light incident surface.

  (3) In the solar cell module according to (2), the wavelength converter may be disposed on the surface of the light collector opposite to the light incident surface via an air layer.

  (4) In the solar cell module according to the above (2) or (3), the wavelength converter may include a plurality of particles made of an inorganic wavelength conversion material.

  (5) In the solar cell module according to (4), a gap may be formed between two particles adjacent to each other.

  (6) In the solar cell module according to any one of (2) to (5), a reflection plate may be disposed on the side of the wavelength converter opposite to the light collector. .

  (7) In the solar cell module according to (6), the wavelength converter may be formed on a surface of the reflector on the light collector side.

  (8) In the solar cell module according to any one of (2) to (7), the wavelength converter includes at least light that has passed through the light collecting plate among light incident on the light incident surface. Some may be scattered.

  (9) In the solar cell module according to (1), the wavelength converter may be included in the light collector.

  (10) In the solar cell module according to (9), at least a part of the wavelength converter may include a plurality of particles made of an organic wavelength conversion material.

  (11) In the solar cell module according to (9) or (10), at least a part of the wavelength converter may include a plurality of particles made of an inorganic wavelength conversion material.

  (12) In the solar cell module according to any one of (1) to (11), the peak wavelength of the absorption spectrum of any one or the plurality of optical functional materials and the emission spectrum of the wavelength converter. The peak wavelength may substantially match.

  (13) In the solar cell module according to (12), the plurality of optical functional materials are different types of optical functional materials, and at least one type of optical functional material among the plurality of types of optical functional materials. The peak wavelength of the absorption spectrum may substantially coincide with the peak wavelength of the emission spectrum of the wavelength converter.

  (14) In the solar cell module according to (12) or (13), the wavelength converter is a plurality of types of wavelength converters different from each other, and at least one type of wavelength converter among the plurality of types of wavelength converters. The peak wavelength of the light emission spectrum of the body may substantially coincide with the peak wavelength of the absorption spectrum of any one of the one or more optical functional materials.

  (15) In the solar cell module according to any one of (1) to (14), the wavelength converter includes at least light that has not been absorbed by any of the one or more optical functional materials. A part of the light may be converted into light having a shorter wavelength than light that has not been absorbed by any of the one or more optical functional materials.

  (16) In the solar cell module according to (15), the wavelength range of light absorbed by any of the wavelength converters is the wavelength of light absorbed by any of the one or more optical functional materials. The wavelength may be longer than the region.

  (17) In the solar cell module according to (16), the wavelength converter includes a light emission center that interacts with light that is not absorbed by any of the one or more optical functional materials, and the light emission. The center may have a first excited state having an energy gap equal to or less than the energy of the light that has not been absorbed by any of the one or more optical functional materials between the center and the ground state.

  (18) In the solar cell module according to (17), the emission center is higher than energy of light that is not absorbed by any of the one or more optical functional materials between the ground state and the ground state. You may have the 2nd excitation state with an energy gap.

  (19) In the solar cell module according to (18), electronic transition between the first excited state and the ground state may be prohibited.

  (20) In the solar cell module according to (19), the emission center may include an element having open-shell f electrons.

  (21) In the solar cell module according to (20), the element may be a rare earth element.

  (22) In the solar cell module according to (20) or (21), the element may be Er (erbium), Tm (thulium), or Ho (holmium).

  (23) In the solar cell module according to any one of (16) to (22), the wavelength converter may include a sensitizer.

  (24) In the solar cell module according to (23), the sensitizer may be Yb (ytterbium).

  (25) The solar power generation device according to the first aspect of the present invention includes the solar cell module according to any one of (1) to (24) above.

  ADVANTAGE OF THE INVENTION According to this invention, the solar cell module and solar power generation device which can obtain high electric power generation efficiency can be provided.

It is sectional drawing which shows the solar cell module which concerns on 1st Embodiment. It is a top view which shows the solar cell module which concerns on 1st Embodiment. It is sectional drawing along the AA line of FIG. It is a figure which shows an example of the energy diagram of the luminescent center of a multiphoton excitation fluorescent substance. It is a figure which shows an example of the energy diagram of a multiphoton excitation fluorescent substance. It is a figure for demonstrating an effect | action of the solar cell module which concerns on the comparative example 1. FIG. It is a figure for demonstrating the wavelength range which a light-condensing plate absorbs among sunlight spectrums in the solar cell module which concerns on the comparative example 1. FIG. It is a figure which shows the wavelength dependence of the conversion efficiency of a solar cell element. It is a figure which shows the relationship between the maximum wavelength which a fluorescent substance can absorb among sunlight spectra in the solar cell module which concerns on the comparative example 1, and the wavelength corresponded to the band gap of a solar cell element. It is a figure for demonstrating the effect | action of the solar cell module which concerns on 1st Embodiment. In the solar cell module which concerns on 1st Embodiment, it is a figure for demonstrating the wavelength range which a fluorescent substance absorbs among the sunlight spectrum, and the wavelength range which a wavelength conversion body converts. It is a figure for demonstrating the absorption spectrum of fluorescent substance. It is a figure for demonstrating the total reflection in case a wavelength converter is a layer which consists of organic wavelength conversion materials. It is a figure for demonstrating surface scattering in case a wavelength converter contains the some particle | grains which consist of inorganic wavelength conversion materials. It is a figure for demonstrating the light transmission in case a wavelength converter is a layer which consists of organic wavelength conversion materials. It is a figure for demonstrating surface reflection in case a wavelength converter contains the some particle | grains which consist of inorganic wavelength conversion materials. It is a figure for demonstrating the light transmission in a light-condensing plate in the solar cell module which concerns on 1st Embodiment. It is a figure for demonstrating the light transmission in a single crystal type solar cell in the solar cell module which concerns on the comparative example 2. FIG. It is a figure for demonstrating the light transmission in a polycrystalline solar cell in the solar cell module which concerns on the comparative example 3. FIG. It is a figure which shows the transmission spectrum of ITO (ITO film | membrane). It is a figure which shows the transmission spectrum of an acryl (PMMA). It is a figure which shows the transmission spectrum of the light-condensing plate which concerns on 1st Embodiment. 6 is a cross-sectional view of a single crystal solar cell in a solar cell module according to Comparative Example 2. FIG. It is sectional drawing which shows the solar cell module which concerns on 2nd Embodiment. It is a figure which shows the spectrum (air mass 1.5) of sunlight. It is a figure which shows each absorption spectrum of 4 types of fluorescent substance, and the absorption spectrum of the light-condensing plate which mixed 4 types of fluorescent substance. It is a figure which shows the absorption spectrum of the light-condensing plate which mixed 4 types of fluorescent substance. It is a figure which shows the sunlight spectrum which permeate | transmits the light collector which mixed 4 types of fluorescent substance with the transmission spectrum of the light collector which mixed the sunlight spectrum and 4 types of fluorescent substance. NaYF 4 as a multi-photon excitation fluorescent material: _Er, is a graph showing an emission spectrum and an excitation spectrum when using Yb. NaYF 4 as a multi-photon excitation fluorescent material: _Er, is a diagram showing the relationship between the emission spectrum and the 4 types of the absorption spectrum of the light collecting plate of the phosphor mixed when using Yb. It is a figure which shows each absorption spectrum of three types of fluorescent substance, and the absorption spectrum of the light-condensing plate which mixed three types of fluorescent substance. It is a figure which shows the absorption spectrum of the light-condensing plate which mixed three types of fluorescent substance. It is a figure which shows the sunlight spectrum which permeate | transmits the light collector which mixed 3 types of fluorescent substance with the transmission spectrum of the light collector which mixed the sunlight spectrum and 3 types of fluorescent substance. _Gd 2 _{(WO 4)} 3 as a multiphoton excitation phosphor: Tm, is a graph showing an emission spectrum and an excitation spectrum when using Yb. Gd 2 _(WO 4) 3 as a multiphoton excitation _{phosphor: Tm,} it is a diagram showing the relationship between the emission spectrum and the three absorption spectra of the light collecting plate of the phosphor mixed when using Yb. It is sectional drawing which shows the solar cell module which concerns on 3rd Embodiment. It is sectional drawing which shows the solar cell module which concerns on 4th Embodiment. It is sectional drawing which shows the solar cell module which concerns on 5th Embodiment. It is sectional drawing which shows the solar cell module which concerns on 6th Embodiment. It is a schematic block diagram of a solar power generation device. It is a figure which shows the sunlight spectrum which permeate | transmits the light collector which mixed 5 types of fluorescent substance with the transmission spectrum of the light collector which mixed the sunlight spectrum and 5 types of fluorescent substance. The emission spectrum, absorption spectrum, and absorption energy spectrum of Phosphor Technology Ltd (UK) manufactured as a multi-photon excitation phosphor are transmitted through a light collecting plate containing a sunlight spectrum and five types of phosphors. It is a figure shown with a sunlight spectrum. The emission spectrum, absorption spectrum, and absorption energy spectrum when Er ³⁺ alone activated as a multi-photon excitation phosphor are used, the sunlight spectrum, and the sunlight spectrum that passes through the light collecting plate in which five kinds of phosphors are mixed. It is a figure shown with. Emission spectrum, absorption spectrum, and absorption energy spectrum when using Yb ³⁺ , Er ³⁺ co-activated as a multi-photon excitation phosphor are transmitted through a condensing plate containing a sunlight spectrum and five types of phosphors. It is a figure shown with a sunlight spectrum.

[First embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
In all of the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

  FIG. 1 is a cross-sectional view showing a solar cell module 1 according to the first embodiment.

  As shown in FIG. 1, the solar cell module 1 includes a light collector 2, a solar cell element 3, a wavelength converter 7, and a reflector 8.

  The light collector 2 has a first main surface 2a, a second main surface 2b, and an end surface 2c. The first main surface 2a is a light incident surface. The second main surface 2b is a surface opposite to the first main surface 2a. The end surface 2c is a light emission surface.

  The light collector 2 is a fluorescent light collector in which the phosphor 21 is dispersed in the transparent substrate 20. The transparent resin 20 is made of an acrylic resin such as PMMA (polymethyl methacrylate resin), a highly transparent organic material such as a polycarbonate resin, or a transparent inorganic material such as glass. As PMMA resin, acrylite (registered trademark) manufactured by Mitsubishi Rayon Co., Ltd. is preferable because it has high translucency for a wide wavelength range.

  In this embodiment, PMMA resin (refractive index 1.49) is used as the transparent substrate 20. The light collector 2 is formed by dispersing the phosphor 21 in this PMMA resin. Note that the refractive index of the light collector 2 is 1.50, which is about the same as that of the PMMA resin because the amount of the phosphor 21 dispersed is small.

The phosphor 21 is an optical functional material that absorbs ultraviolet light or visible light, emits visible light or infrared light, and emits it. Examples of the optical functional material include organic phosphors.
Such organic phosphors include coumarin dyes, perylene dyes, phthalocyanine dyes, stilbene dyes, cyanine dyes, polyphenylene dyes, xanthene dyes, pyridine dyes, oxazine dyes, chrysene dyes, thioflavine Dyes, perylene dyes, pyrene dyes, anthracene dyes, acridone dyes, acridine dyes, fluorene dyes, terphenyl dyes, ethene dyes, butadiene dyes, hexatriene dyes, oxazole dyes, coumarins Dyes, stilbene dyes, di- and triphenylmethane dyes, thiazole dyes, thiazine dyes, naphthalimide dyes, anthraquinone dyes and the like are preferably used. Specifically, 3- (2′- Benzothiazolyl) -7-diethylaminocoumarin (bear) Phosphorus 6), 3- (2′-Benzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 7), 3- (2′-N-methylbenzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 30) , 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidine (9,9a, 1-gh) coumarin (coumarin 153) and other coumarin dyes, and basic coumarin dyes Naphthalimide dyes such as yellow 51, solvent yellow 11 and solvent yellow 116; rhodamine dyes such as rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, sulforhodamine, basic violet 11 and basic red 2; 1-ethyl-2- [4- (p-dimethyl) Aminophenyl) -1,3-butadienyl] pyridinium - perchlorate (pyridine 1) pyridine dyes such as news, cyanine dyes, or the like oxazine dyes are used.

An inorganic phosphor can also be used as the phosphor.
Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used as the phosphor of the present invention as long as they have fluorescence.

  In the case of the present embodiment, one type of phosphor 21 is dispersed inside the light collector 2. The phosphor 21 absorbs orange light and emits red fluorescence. In the present embodiment, BASF Lumogen R305 (trade name) is used as the phosphor 21. The phosphor 21 absorbs light having a wavelength of approximately 600 nm or less. The emission spectrum of the phosphor 21 has a peak wavelength at 610 nm.

  In addition, you may use not only the case where 1 type of fluorescent substance is used but multiple types (2 types or 3 types or more) fluorescent substance.

  When two or more phosphors are used in combination, energy transfer is caused between these phosphors by the Forster mechanism, and light emitted from the phosphor having the largest peak wavelength of the emission spectrum is emitted to the solar cell element. You may comprise as follows.

  In the Förster mechanism, excitation energy is directly transferred by resonance of electrons between two adjacent phosphors without going through light generation and absorption processes. Since energy transfer between phosphors by the Förster mechanism is performed without going through the process of light generation and absorption, the energy transfer efficiency can be almost 100% under optimum conditions, and energy loss is reduced. small. Therefore, it contributes to the improvement of the power generation efficiency of the solar cell module. In order to efficiently generate power while suppressing energy loss, for example, the density of the phosphor used in combination in the transparent substrate may be increased.

  In addition, energy transfer by the Forster mechanism occurs not only in a light emitting material such as a phosphor but also in a non-light emitting body that is excited by external light but deactivates without generating light. Therefore, in addition to the phosphor, such a non-luminous material may be dispersed in the transparent substrate as an optical functional material.

In the solar cell element 3, the light receiving surface is arranged to face the end surface 2 c of the light collector 2. As the solar cell element 3, a known solar cell such as a silicon solar cell, a compound solar cell, a quantum dot solar cell, or an organic solar cell can be used. Especially, the compound type solar cell and quantum dot solar cell using a compound semiconductor are suitable as the solar cell element 3 since highly efficient electric power generation is possible. In particular, a GaAs solar cell which is a compound solar cell exhibiting high efficiency at the peak wavelength (610 nm) of the emission spectrum of the phosphor 21 is desirable. In addition, InGaP, InGaAs, AlGaAs, Cu (In, Ga) Se ₂ , Cu (In, Ga) (Se, S) ₂ , CuInS ₂ , CdTe, CdS, or the like may be used as the compound solar cell. . Further, Si, InGaAs or the like may be used as the quantum dot solar cell. However, other types of solar cells such as Si and organic can be used depending on the price and application.

  The solar cell element 3 is joined to the end surface 2 c of the light collector 2 by a transparent adhesive 6. The transparent adhesive 6 is preferably a thermosetting adhesive such as an ethylene / vinyl acetate copolymer (EVA), an epoxy adhesive, a silicone adhesive, or a polyimide adhesive. Note that the refractive index of the transparent adhesive 6 is 1.50, which is about the same as that of the light collector 2. Instead of the transparent adhesive 6, a liquid or gel optical contact material may be used. For example, the optical contact material has transparency such as optical oil (immersion oil: refractive index 1.51) used for an optical microscope having an immersion lens, and has substantially the same refractive index as the light collector 2. It may be a material.

Next, an example of the holding | maintenance state of the light-condensing plate 2 and the solar cell element 3 is demonstrated using FIG.2 and FIG.3.
FIG. 2 is a plan view showing the solar cell module 1 according to the first embodiment. 3 is a cross-sectional view taken along line AA in FIG.

  As shown in FIG. 2, the light collector 2 is a plate member having a rectangular shape in plan view. As an example, the size of the light collector 2 is such that the length of the long side is about 100 cm, the length of the short side is about 90 cm, and the thickness is about 4 mm.

  The solar cell element 3 is installed on the four end surfaces 2 c of the light collector 2. The number of installed solar cell elements 3 is not limited to this, and the solar cell elements 3 may be installed on one to three end surfaces 2 c of the light collector 2.

  When the solar cell element 3 is installed on a part of the end surface (one side, two sides, or three sides) of the light collector 2, it is preferable to install a reflective layer on the end surface where the solar cell element is not installed.

  As the reflective layer, a reflective layer made of a dielectric multilayer film such as an ESR (Enhanced Specular Reflector) reflective film (manufactured by 3M) can be used. If this material is used, a high reflectance of 98% or more can be realized under visible light. As the reflective layer, a reflective layer made of a metal film such as aluminum (Al), copper (Cu), gold (Au), silver (Ag), or the like may be used.

  The frame 4 has a rectangular frame shape in plan view. The frame 4 holds the light collector 2. The frame 4 is formed so as to cover the solar cell element 3. The thickness of the frame 4 is about 2 mm. The material for forming the frame 4 is a metal such as Al. In addition, various materials can be used as the material for forming the frame 4. In particular, it is preferable to use a high-strength and lightweight material.

  As shown in FIGS. 2 and 3, the position regulating member 5 is provided at a portion where the light collector 2 and the frame 4 overlap each other when viewed from the normal direction of the first main surface 2 a. The position regulating member 5 regulates the relative position between the light collector 2 and the frame 4. Specifically, the position regulating member 5 regulates the relative position between the light collector 2 and the frame 4 in a direction parallel to the first main surface 2a and a direction perpendicular to the first main surface 2a.

  The light collector 2 is provided with a through hole 20h. A screw is used as the penetrating member of the position regulating member 5. The screw 5 is fixed to the frame 4.

  A metal is used as a material for forming the screw 5. In addition, various materials can be used as the material for forming the screw 5. In particular, it is preferable to use an alloy such as stainless steel (SUS) from the viewpoint of obtaining high strength.

  As shown in FIG. 2, the frame 4 is divided for each side of the light collector 2. The frame 4 includes a first subframe 41 and a second subframe 42. The first subframe 41 is disposed along the short side of the light collector 2. Two first subframes 41 are arranged, one on each of the two short sides facing each other. The second subframe 42 is disposed along the long side of the light collector 2. Two second subframes 42 are arranged, one on each of the two long sides facing each other.

  The screw hole 41h is provided in a portion overlapping the through hole 20h of the first subframe 41. The end portion of the first subframe 41 is fixed to the end portion of the second subframe 42 by a fixing member 43 such as a screw.

  As shown in FIG. 3, the frame 4 includes a top plate portion 4a, a bottom plate portion 4b, and a side wall portion 4c. Here, the structure of the frame 4 will be described with reference to a diagram in which the first sub-frame 41 includes a top plate 41a, a bottom plate 41b, and a side wall 41c. The configuration of the second subframe 42 has the same configuration as this.

  The top plate portion 41 a is formed so as to cover the solar cell element 3. One end of the top plate portion 41a is connected to the side wall portion 41c. The other end portion of the top plate portion 41 a extends to the end portion of the first main surface 2 a of the light collector 2. The bottom plate portion 41b is disposed to face the top plate portion 41a with the light collector 2 interposed therebetween. One end portion of the bottom plate portion 41b is connected to the side wall portion 41c. The other end portion of the bottom plate portion 41 b extends to a portion exceeding the through hole 20 h of the light collector 2. The length in the longitudinal direction of the light collector 2 of the bottom plate portion 41b is longer than the length in the longitudinal direction of the light collector 2 of the top plate 41a. The screw hole 41h is provided in a portion of the bottom plate portion 41b that extends from the top plate portion 41a.

  In the bottom plate portion 41 b, a spacer 45 is provided between the light collector 2 and the reflector 8. The height of the spacer 45 is larger than the thickness of the wavelength converter 7. A reflective film 46 is provided between the spacer 45 and the light collector 2. The reflective film 46 can use ESR.

  The inner wall surface 4s of the frame 4 and the solar cell element 3 are separated from each other. A space 40 is provided between the inner wall surface 41 s of the first subframe 41 and the surface 3 s opposite to the light receiving surface of the solar cell element 3. An air layer is interposed in the space 40.

  In addition, although the structure of the flame | frame 4 was demonstrated in detail using FIG. 3, it is not restricted to this. The configuration of the frame 4 described with reference to FIG. 3 is an example, and the present invention can be applied even when a frame other than this configuration is used.

  Returning to FIG. 1, the wavelength converter 7 is disposed on the second main surface 2 b side of the light collector 2 via the air layer 9. Thereby, since the refractive index difference between the refractive index of the light collector 2 and the refractive index of the air layer 9 is large, the light propagating through the light collector 2 is totally reflected at the interface between the light collector 2 and the air layer 9. Light loss can be reduced. For example, if the refractive index of the light collector 2 is 1.5 and the refractive index of the air layer 9 is 1.0, the critical angle at the interface between the light collector 2 and the air layer 9 is about 42 ° from Snell's law. . Since the critical angle condition is satisfied while the incident angle of light on the interface is greater than the critical angle of 42 °, the light is totally reflected at the interface.

  The wavelength converter 7 may be disposed in contact with the second main surface 2b of the light collector 2. However, from the viewpoint of reducing light loss, the wavelength converter 7 is preferably disposed on the second main surface 2b side of the light collector 2 via the air layer 9.

  The wavelength converter 7 absorbs light that has not been absorbed by the phosphor 21 out of light incident on the first main surface 2 a of the light collector 2, converts it into light that is absorbed by the phosphor 21, and emits it. The wavelength converter 7 converts at least a part of the light that is not absorbed by the phosphor 21 into light having a shorter wavelength than the light that is not absorbed by the phosphor 21. The wavelength range of light absorbed by the wavelength converter 7 is longer than the wavelength range of light absorbed by the phosphor 21. The wavelength converter 7 scatters at least a part of the light transmitted through the light collector 2 out of the light incident on the first main surface 2 a of the light collector 2.

  The wavelength converter 7 according to the present embodiment includes a plurality of particles 70 made of an inorganic wavelength conversion material. A void 71 is formed between two particles 70 adjacent to each other. For example, the particle 70 is a multiphoton excitation phosphor.

  On the opposite side of the wavelength converter 7 from the light collector 2, a reflector 8 is disposed. The wavelength converter 7 is formed on the surface of the reflector 8 on the light collector 2 side.

  The reflector 8 can use ESR. If this material is used, a high reflectance of 98% or more can be realized under visible light. In addition, as the reflecting plate 8, a metal plate such as aluminum (Al), copper (Cu), gold (Au), silver (Ag), or the like may be used. Moreover, as the reflector 8, you may use what has diffuse reflectivity, such as micro foaming PET (polyethylene terephthalate) by Furukawa Electric.

Hereinafter, the light emission principle of the multiphoton excitation phosphor will be described with reference to FIGS.
FIG. 4 is a diagram showing an example of an energy diagram of the emission center of the multiphoton excitation phosphor.

  The multiphoton excitation phosphor (wavelength converter) has an emission center that interacts with light that has not been absorbed by the phosphor 21. The multiphoton excitation phosphor is a solid material such as an inorganic material, an organic material, or a polymer, or a sealed liquid material. The multiphoton excitation phosphor has ions or molecules (light emission centers) that absorb or emit light.

  As shown in FIG. 4, the emission center has a first excited state E <b> 1 having an energy gap equal to or less than the energy of the light that has not been absorbed by the phosphor 21, with the ground state E <b> 0. The emission center has a second excited state E2 having an energy gap higher than that of light that has not been absorbed by the phosphor 21 between the emission state and the ground state E0.

The light emission center first absorbs light once and is excited from the ground state E0 to the first excited state E1. Next, the emission center absorbs light again and is excited from the first excited state E1 to the second excited state E2. The emission center existing in the second excited state E2 transitions from the second excited state E2 to the ground state E0 and emits light having a shorter wavelength than the two absorbed lights.
Although FIG. 4 shows the case where the number of times of light absorption is two, it may be three or more.

  Electronic transition between the first excited state E1 and the ground state E0 may be prohibited. Thereby, long wavelength light can be converted into a short wavelength (up-conversion) with a high quantum yield. The reason is as follows.

  In order to up-convert with a high quantum yield, the emission center needs to remain in the first excited state E1 until it absorbs the first light and then absorbs the second light. This is because it is necessary to suppress the transition of the emission center from the first excited state E1 to the ground state E0. Therefore, it is desirable that electronic transition between the ground state E0 and the first excited state E1 is forbidden.

  Examples of the fact that electronic transition between the ground state E0 and the first excited state E1 is forbidden include ss transition (electron transition between s orbitals) and sd transition (between s and d orbitals). Electron transition), pp transition (electron transition between p orbitals), pf transition (electron transition between p and f orbitals), dd transition (electron transition between d orbitals), ff Transition (electron transition between f orbitals).

  Among these, electron transitions between orbitals localized near the nucleus such as dd transition and ff transition are desirable. The reason is that the d orbit and f orbital are localized in the vicinity of the nucleus compared to the s and p orbitals, and the forbidden collapse due to the crystal field is small, so that the d orbit remains in the first excited state E1 for a long time. Because it is possible. In particular, the ff transition is preferable. The reason is that the ff transition is more localized than the dd transition.

  The details of the light emission principle of the multiphoton excitation phosphor are described in Non-Patent Document 1: “Chemical Reviews 2004, vol. 104, No. 1”.

The emission center may contain an element having open shell f electrons. The element having open-shell f electrons is a rare earth element such as Er (erbium), Tm (thulium), or Ho (holmium). The reason is that ions having an open shell f orbital such as Er ³⁺ (erbium ion), Tm ³⁺ (thulium ion), or Ho ³⁺ (holmium ion) can be excited by the ff transition.

FIG. 5 is a diagram showing an example of an energy diagram of the multiphoton excitation phosphor.
The left part of FIG. 5 is an energy diagram in the case of Er ³⁺ single activation, and the right part of FIG. 5 is the energy diagram in the case of Yb ³⁺ and Er ³⁺ co-activation. In FIG. 5, the vertical axis represents the wave number [10 ⁴ cm ⁻¹ ]. In FIG. 5, symbols such as ⁴ S _3/2 , ⁴ l _9/2 , and ⁴ l _15/2 are symbols representing the electron configuration at each energy level. When the total orbital angular momentum is L, the total spin angular momentum is S, and the total angular momentum is J, it is expressed as “ ^{2S + 1} L _J ”.

  As shown in FIG. 5, the f orbital is localized near the nucleus more than the s orbital, p orbital, and d orbital, and the forbidden collapse caused by the crystal field is less, so it stays in the first excited state E1 for a long time. It is possible that Therefore, the ff transition is optimal as the electronic transition between the ground state E0 and the first excited state E1.

The multiphoton excitation phosphor may contain a sensitizer. The sensitizer is, for example, Yb (ytterbium). When the multiphoton excitation phosphor has Yb ³⁺ (ytterbium ion), first Yb ³⁺ is excited with light, and then energy is transferred from Yb ³⁺ to the emission center (for example, Er ³⁺ , Tm ³⁺ , or Ho ³⁺ ). Also good. Thereby, since the density ^| concentration of Yb3 ⁺ as a sensitizer and the density ^| concentration of a luminescent center can each be optimized independently, the multiphoton excitation fluorescent substance with a higher quantum yield is producible.

Particularly, is made higher than the concentration of luminescence center concentration of Yb ^3+, can collect light absorbed by the Yb ³⁺ concentration is low emission center than Yb ^3+. Therefore, excitation from the first excited state E1 to the second excited state E2 can be easily generated, and as a result, the quantum yield can be improved.

  For example, as the multiphoton excitation phosphor, materials shown in Table 1 are used, but are not limited thereto.

In Table 1, the left side of the column of material is a host crystal, and the right side of the column of material is an activating element. Excitation intensity [mW] (excitation density [W / cm ² ]), λemi [nm] (peak wavelength of emission spectrum), and η [%] (number of emitted photons / number of absorbed photons) This is a value when the material of the multiphoton excitation phosphor is excited by use.

In addition, the multiphoton excitation phosphor may be a polymer containing a metal complex having Er ³⁺ , Tm ³⁺ , or Ho ³⁺ , even if it is not the inorganic material shown in Table 1, Non-patent Document 2: “Chemical Physics letters 2011, vol. 516, 56 "may be a layer sealed with an ionic fluid.

  Hereinafter, the effect | action of the solar cell module 1 which concerns on this embodiment is demonstrated using FIGS. 6-23, comparing with the solar cell module (Comparative example 1, Comparative example 2, and Comparative example 3) which concerns on a comparative example. .

  First, the operation of the solar cell module 1 according to the present embodiment will be described by comparing the present embodiment with Comparative Example 1.

FIG. 6 is a diagram for explaining the operation of the solar cell module 2001 according to Comparative Example 1.
As shown in FIG. 6, the solar cell module 2001 according to Comparative Example 1 includes a light collector 2 and a solar cell element 3. The solar cell module 2001 does not include the wavelength converter 7 and the reflector 8.

FIG. 7 is a diagram for explaining a wavelength range absorbed by the light collector 2 in the solar spectrum in the solar cell module 2001 according to Comparative Example 1. In FIG. 7, the horizontal axis represents wavelength [nm], and the vertical axis represents intensity [W / m ² / nm].

  As shown in FIG. 7, most of the sunlight spectrum Sp (air mass 1.5) is distributed in a wavelength range of 300 nm to 1800 nm. The absorption spectrum Sp1 of the phosphor 21 is distributed in a wavelength range of 300 nm to 600 nm. In this case, sunlight having a wavelength longer than the maximum wavelength (600 nm) that the phosphor 21 can absorb cannot be used for power generation.

  As shown in FIG.6 and FIG.7, in the solar cell module 2001 which concerns on the comparative example 1, although the fluorescent substance 21 can absorb the light L1 of a 300 nm-600 nm wavelength range among sunlight spectra, it is 600 nm. It is not possible to absorb the light L2 in the wavelength region that exceeds. Therefore, light L2 in a wavelength region exceeding 600 nm in the sunlight spectrum passes through the light collector 2 and does not contribute to power generation. Therefore, high power generation efficiency cannot be obtained.

  The phosphor 21 absorbs sunlight and emits light at a wavelength at which the light-power conversion efficiency of the solar cell element 3 (efficiency for converting light into electric power, hereinafter simply referred to as “conversion efficiency”) is high. To do. Therefore, the maximum wavelength that the phosphor 21 can absorb needs to be smaller than the maximum wavelength of the conversion efficiency of the solar cell element 3.

  FIG. 8 is a diagram showing the wavelength dependence of the conversion efficiency of the solar cell element 3. In FIG. 8, the horizontal axis represents wavelength [nm] and the vertical axis represents conversion efficiency [%]. In FIG. 8, the wavelength (870 nm) corresponding to the band gap of the GaAs solar cell is the wavelength λg1, and the wavelength (1120 nm) corresponding to the band gap of the c-Si solar cell is the wavelength λg2.

  As shown in FIG. 8, the conversion efficiency of each of the crystalline silicon (c-Si) solar cell, GaAs solar cell, CuInGaSe-based mixed crystal solar cell (CIGS solar cell), and InGaP solar cell is the material of each solar cell element. Conversion efficiency is maximized at a wavelength determined by the band gap. For example, in the case of a c-Si solar cell, the conversion efficiency becomes maximum at a wavelength slightly shorter than the wavelength λg (1120 nm) corresponding to the band gap. In the case of a GaAs solar cell, the conversion efficiency becomes maximum near the wavelength λg1 (870 nm) corresponding to the band gap. Then, the longer wavelength side is steeply lowered, and the conversion efficiency is slowly lowered on the shorter wavelength side.

  FIG. 9 is a diagram illustrating the relationship between the maximum wavelength that can be absorbed by the phosphor 21 in the solar cell module according to Comparative Example 1 and the wavelength corresponding to the band gap of the solar cell element 3. In FIG. 9, the horizontal axis represents wavelength [nm] and the vertical axis represents conversion efficiency [%].

  As shown in FIG. 9, for example, the maximum wavelength (600 nm) that can be absorbed by the phosphor 21 is the wavelength λm, the wavelength corresponding to the band gap of the GaAs solar cell (870 nm) is the wavelength λg1, and the band gap of the c-Si solar cell. The corresponding wavelength (1120 nm) is defined as wavelength λg2. In this case, the wavelength λm must be shorter than the wavelengths λg1 and λg2. The wavelengths λg1 and λg2 are values determined by the material of the solar cell. For this reason, there is a limit to increasing the wavelength λm.

FIG. 10 is a diagram for explaining the operation of the solar cell module 1 according to the present embodiment.
As shown in FIG. 10, the solar cell module 1 according to this embodiment includes a light collector 2, a solar cell element 3, a wavelength converter 7, and a reflector 8. The wavelength converter 7 is arranged on the second main surface 2 b side of the light collector 2 via the air layer 9. The wavelength converter 7 is formed on the surface of the reflector 8 on the light collector 2 side.

FIG. 11 is a diagram for explaining the wavelength range absorbed by the light collector 2 and the wavelength range converted by the wavelength converter 7 in the solar spectrum in the solar cell module 1 according to the present embodiment. In FIG. 11, the horizontal axis represents wavelength [nm] and the vertical axis represents intensity [W / m ² / nm].

  As shown in FIG. 11, most of the sunlight spectrum Sp (air mass 1.5) is distributed in a wavelength range of 300 nm to 1800 nm. The absorption spectrum Sp1 of the phosphor 21 is distributed in a wavelength range of 300 nm to 600 nm. In this case, sunlight having a wavelength longer than the maximum wavelength (600 nm) that the phosphor 21 can absorb cannot be used for power generation.

  As shown in FIGS. 10 and 11, the phosphor 21 can absorb light L1 in the wavelength region of 300 nm to 600 nm in the sunlight spectrum, but it absorbs light L2 in the wavelength region exceeding 600 nm. Can not. Therefore, light L <b> 2 having a wavelength region exceeding 600 nm in the sunlight spectrum is transmitted through the light collector 2. The light L2 in this wavelength band was not used at all in Comparative Example 1.

  However, in the solar cell module 1 according to the present embodiment, the absorption spectrum Sp2 of the wavelength converter 7 exists in at least a part of the wavelength range of 600 nm to 1800 nm. Therefore, a part of the light L2 that has passed through the light collector 2 is absorbed by the wavelength converter 7, converted into light L3 that can be absorbed by the phosphor 21, and emitted. As a result, the light L3 converted by the wavelength converter 7 is absorbed by the phosphor 21, so that light that has not been used in Comparative Example 1 can contribute to power generation.

  In the present embodiment, the amount of power generation can be increased by simply adding the wavelength converter 7 and the reflecting plate 8 to the solar cell module 2001 according to Comparative Example 1 without significantly changing other configurations.

  In the present embodiment, it is preferable that the wavelength range of the light L3 emitted from the wavelength converter 7 and the wavelength range absorbed by the phosphor 21 overlap as much as possible. For example, the peak wavelength of the absorption spectrum of the phosphor 21 and the peak wavelength of the emission spectrum of the wavelength converter 7 are generally matched. Here, “substantially match” is defined as follows.

The term “substantially matches” means that the peak wavelength of the emission spectrum of the wavelength converter 7 is included in the “first wavelength range” shown below.
The “first wavelength range” is “the absorbance (or absorbance) of the phosphor 21 is 0 when the absorbance (or absorbance) at the peak wavelength of the absorption spectrum of the phosphor 21 is 1 in the wavelength range of 300 nm to 1000 nm. .Wavelength range that is greater than or equal to 1. "

  FIG. 12 is a diagram for explaining the absorption spectrum of the phosphor. In FIG. 12, the horizontal axis represents wavelength [nm] and the vertical axis represents absorbance [a.u.]. Further, the peak wavelength of the absorption spectrum of the phosphor is λp. Further, assuming that the absorbance at the peak wavelength λp of the absorption spectrum of the phosphor is 1, the wavelength at which the absorbance becomes 0.5 is 0.5λ1, 0.5λ2 (where 0.5λ1 <λp <0.5λ2), and the absorbance. Is a wavelength at which 0.1 becomes 0.1λ1, 0.1λ2 (where 0.1λ1 <λp <0.1λ2).

  For example, in the case of FIG. 12, the “first wavelength range” is 0.1λ1 ≦ λ ≦ 0.1λ2. Here, the peak wavelength λp of the absorption spectrum of the phosphor is a wavelength at which the absorbance of the phosphor 21 is maximum in the wavelength range of 300 nm to 1000 nm. Since the “first wavelength range” is the absorption band of the phosphor 21, it is possible to absorb the light emitted from the wavelength converter 7.

Moreover, it is more preferable that the peak wavelength of the emission spectrum of the wavelength converter 7 is included in the “second wavelength range” shown below.
The “second wavelength range” is “in the wavelength range of 300 nm to 1000 nm, where the absorbance (or absorbance) at the peak wavelength of the absorption spectrum of the phosphor 21 is 1, the absorbance (or absorbance) of the phosphor 21 is 0. Is defined as a wavelength region that is .5 or more.

  For example, in the case of FIG. 12, the “second wavelength range” is 0.5λ1 ≦ λ ≦ 0.5λ2. The “second wavelength range” is the range of the full width at half maximum of the peak wavelength λp of the absorption spectrum of the phosphor, and is in the vicinity of the absorption peak wavelength λp of the phosphor 21, so that the wavelength converter 7 can emit light more efficiently and sufficiently. Can be absorbed.

Moreover, although the wavelength converter 7 may consist of an inorganic wavelength conversion material and may consist of an organic wavelength conversion material, it is preferable that it is a laminated film of the several particle | grains which consist of an inorganic wavelength conversion material. More preferably, an air gap (air or low refractive medium) is formed between two adjacent particles.
Hereinafter, the reason will be described with reference to FIGS.

FIG. 13 is a diagram for explaining total reflection when the wavelength converter 207 is a layer made of an organic wavelength conversion material.
FIG. 14 is a diagram for explaining the surface scattering when the wavelength converter 7 includes a plurality of particles 70 made of an inorganic wavelength conversion material.

  As shown in FIG. 13, the solar cell module 101 is a layer in which the wavelength converter 207 is made of an organic wavelength conversion material. In the case of the solar cell module 101, a light emission component having a critical angle or more determined by a difference in refractive index between the wavelength converter 207 and the air layer 9 out of the light emitted from the wavelength converter 207 is between the wavelength converter 207 and the air layer 9. Total reflection at the interface. Therefore, the emitted light from the wavelength converter 207 may not be extracted sufficiently upward.

  As shown in FIG. 14, the solar cell module 1 includes a plurality of particles 70 in which the wavelength converter 7 is made of an inorganic wavelength conversion material. A void 71 is formed between two particles 70 adjacent to each other. In general, the refractive index of the inorganic wavelength converter is a high refractive index of 1.8 or more. Therefore, in the case of the solar cell module 1, the light emitted isotropically from the particle 70 is refracted and reflected at the interface between the particle 70 and the gap 71, and as a result, has light scattering properties. Therefore, the light emitted isotropically from the particles 70 is scattered and easily extracted upward while traveling through the wavelength converter 7 composed of the peripheral particles 70 and the voids 71.

FIG. 15 is a diagram for explaining light transmission when the wavelength converter 207 is a layer made of an organic wavelength conversion material.
FIG. 16 is a diagram for explaining surface reflection when the wavelength converter 7 includes a plurality of particles 70 made of an inorganic wavelength conversion material.

  As shown in FIG. 15, in the case of the solar cell module 101, the wavelength converter 207 transmits a component in the wavelength region of sunlight (300 nm to 600 nm) (light absorbed by the phosphor 21). Therefore, the light incident on the wavelength converter 207 is reflected on the surface of the reflector 8.

  On the other hand, in the case of the solar cell module 1, as shown in FIG. 16, the wavelength converter 7 has a plurality of interfaces between the particles 70 and the voids 71. Therefore, even if the light absorbed by the phosphor 21 passes through the light collector 2, most of the light transmitted through the light collector 2 cannot enter the wavelength converter 7 deeply. Reflects near the surface. Therefore, even if the reflectance of the reflecting plate 8 is low, even if the reflecting plate 8 is not a reflective material, and no reflecting plate 8 is provided, a high reflectance can be realized.

  Next, the operation of the solar cell module 1 according to this embodiment will be described by comparing this embodiment with Comparative Examples 2 and 3.

  FIG. 17 is a diagram for explaining light transmission through the light collector 2 in the solar cell module 1 according to the present embodiment.

  As illustrated in FIG. 17, light L <b> 10 having a wavelength region exceeding 600 nm in the sunlight spectrum (light having a wavelength region that is not absorbed by the phosphor included in the light collector 2) passes through the light collector 2. The transmittance of the light collector 2 with respect to the light L10 is higher than the transmittance according to Comparative Example 2 and Comparative Example 3. The reason will be described below.

  In the solar cell module 1 according to the present embodiment, the light collector 2 has almost no absorption band for the light L10. Further, the interfaces through which the light L10 passes when passing through the light collector 2 are only the two interfaces of the first main surface 2a and the second main surface 2b. Since the refractive index of the light collector 2 is about 1.5, the surface reflectance at the interface determined by the difference in refractive index with air is smaller than the surface reflectance according to Comparative Example 2 and Comparative Example 3.

  FIG. 18 is a diagram for explaining light transmission in the single crystal solar cell 3003 in the solar cell module 3001 according to Comparative Example 2.

  As illustrated in FIG. 18, the solar cell module 3001 according to Comparative Example 2 includes a surface electrode 3002, a single crystal solar cell 3003, a transparent electrode 3004, and a wavelength converter 3005.

  The surface electrode 3002 is an electrode having light reflectivity. The surface electrode 3002 is arranged in a mesh shape on the light incident surface of the single crystal solar cell 3003. The single crystal solar cell 3003 is, for example, a single crystal silicon solar cell. The transparent electrode 3004 is, for example, ITO (Indium Tin Oxide). The transparent electrode 3004 is disposed on the entire surface opposite to the light incident surface of the single crystal solar cell 3003. The wavelength converter 3005 is formed on the surface of the transparent electrode 3004 opposite to the single crystal solar cell 3003.

  In the solar cell module 3001 according to Comparative Example 2, the transmittance of the single crystal solar cell 3003 with respect to the light L10 depends on the aperture ratio of the surface electrode 3002. In addition, since it has a multilayer structure (a stacked structure of the surface electrode 3002, the single crystal solar cell 3003, and the transparent electrode 3004), there are many interfaces through which the light L10 passes when passing through the single crystal solar cell 3003. Further, the refractive index of a semiconductor material used for solar cells such as silicon (Si) is much higher than the refractive index of the light collector 2. For example, the refractive index of silicon is about 3.8@630 nm. Therefore, the transmittance of the single crystal solar cell 3003 for the light L10 is considered to be smaller than the transmittance of the light collector 2 for the light L10.

  FIG. 19 is a diagram for explaining light transmission in the polycrystalline solar cell 4003 in the solar cell module 4001 according to Comparative Example 3.

  As shown in FIG. 19, a solar cell module 4001 according to Comparative Example 3 includes a solar cell module 3001 according to Comparative Example 2 in that a polycrystalline solar cell 4003 is provided instead of the single crystal solar cell 3003. Different. Since the other configuration is the same as that of Comparative Example 2, the same elements as those of Comparative Example 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The polycrystalline solar cell 4003 is, for example, a polycrystalline silicon solar cell. The polycrystalline solar cell 4003 has many polycrystal interfaces 4003a.

In the solar cell module 4001 according to Comparative Example 3, the transmittance of the polycrystalline solar cell 4003 with respect to the light L10 depends on the aperture ratio of the surface electrode 3002. In addition, since it has a multilayer structure, there are many interfaces through which the light L10 passes when it passes through the polycrystalline solar cell 4003. Further, the refractive index of a semiconductor material used for solar cells such as silicon (Si) is much higher than the refractive index of the light collector 2. Furthermore, since it is a polycrystalline solar cell 4003, there are many interfaces 4003a between polycrystals.
Therefore, it is considered that the transmittance of the polycrystalline solar cell 4003 with respect to the light L10 is smaller than the transmittance of the light collector 2 with respect to the light L10.

  Moreover, in each of the solar cell modules 3001 and 4001 according to the comparative example 2 and the comparative example 3, the back electrode of the solar cell needs to be a transparent electrode, and has high mobility required for the solar cell and A transparent electrode having low sheet resistance and high infrared transparency has not been obtained at present. For example, ITO, which is a typical transparent conductive film, has a sharp decrease in transmittance in a wavelength region longer than 1000 nm.

  Also, for solar cells, it is necessary to increase the area, but using a transparent electrode as the back electrode of the solar cell significantly increases the cost compared to a configuration using a metal material as the back electrode of the solar cell. It becomes. For example, indium (In) is a rare element in ITO, and there is a concern about unstable supply.

  ITO is generally used as a transparent conductive film having a low resistivity. In the case of ITO, the carrier concentration is high in order to increase the conductivity. A substance has a plasma frequency inherent to the substance, and light with lower energy is reflected. The plasma frequency is correlated with the carrier concentration. In the case of ITO, the plasma frequency exists in the near-infrared region, and light having lower energy (long wavelength light) is reflected. Therefore, a material having a high conductivity (high carrier concentration) such as ITO generally has a low transmittance in the near-infrared to infrared wavelength region due to the influence of plasma reflection.

  Hereinafter, for reference, a transmission spectrum of general ITO (ITO film), a transmission spectrum of acrylic (PMMA), and a transmission spectrum of the light collector 2 according to the present embodiment will be described with reference to FIGS. explain.

FIG. 20 is a diagram showing a transmission spectrum of general ITO (ITO film).
FIG. 21 is a diagram showing a transmission spectrum of acrylic (PMMA).
FIG. 22 is a diagram showing a transmission spectrum of the light collector 2 according to this embodiment.
20 to 22, the horizontal axis represents wavelength [nm], and the vertical axis represents transmittance [%].

  As shown in FIG. 20, in the transmission spectrum of ITO, the transmittance is maximized in the vicinity of a wavelength of 600 nm. And the transmittance | permeability falls in the long wavelength side and short wavelength side rather than it. In particular, it can be seen that the transmittance sharply decreases in the wavelength region longer than 1000 nm.

  In FIG. 21, the transmission spectrum of PMMA which changed thickness as the transparent base material 20 of the light-condensing plate 2 which concerns on this embodiment is shown with the transmission spectrum of the inorganic glass as a comparative example. The thickness of PMMA was 2 mm, 3 mm, and 6 mm.

  As shown in FIG. 21, the transmission spectrum of PMMA has the maximum transmittance in the wavelength range of 450 nm to 1100 nm in thicknesses of 2 mm, 3 mm, and 6 mm, respectively. In the wavelength range of this range, the transmittance of PMMA is higher than the transmittance of inorganic glass in each of the thicknesses of 2 mm, 3 mm, and 6 mm.

  As shown in FIG. 22, the transmission spectrum of the light collector 2 according to the present embodiment has the maximum transmittance in a long wavelength region of 650 nm or more.

  Next, with respect to the point that the configurations according to Comparative Example 2 and Comparative Example 3 (the configuration in which the back electrode of the silicon solar cell is a transparent electrode) are inferior to the configuration according to this embodiment, refer to FIG. 23 as necessary. However, it will be explained.

  Since silicon has a small absorption coefficient, it is necessary to increase the thickness of silicon in order for silicon to sufficiently absorb sunlight. However, increasing the thickness of silicon increases the cost. Therefore, use highly reflective Ag as the back electrode, or provide a texture structure on the silicon surface to increase the light confinement effect, so that the silicon thickness is as thin as possible and the cost increase is minimized. Has been. However, when the back electrode is made transparent, reflection from the back electrode cannot be obtained. For this reason, in order for silicon to sufficiently absorb sunlight, it is necessary to increase the thickness of silicon as compared with the conventional case in which reflection from the back electrode is obtained, which increases the cost and weight.

In addition, a silicon solar cell includes a front electrode, an n-type silicon layer (hereinafter referred to as an n layer), an i-type silicon layer (hereinafter referred to as an i layer), a p-type silicon layer (hereinafter referred to as a p layer), and a back surface. It consists of a laminated structure of electrodes. A silicon solar cell is asymmetric with respect to the stacking direction.
Thereby, optical power conversion efficiency may differ by the case where light is irradiated from the surface side (surface electrode side), and the case where light is irradiated from the back surface side (back surface electrode side).
Therefore, in a silicon solar cell, compared with the case where light is irradiated from the front surface side (front electrode side), the optical power conversion efficiency when light is irradiated from the back surface side (back electrode side) may be reduced. . The reason is, for example, for the following reason.

  In general, a silicon solar cell is manufactured by forming an n layer on a p-type substrate. This is because the diffusion length of minority carriers is larger for electrons than holes, so that the n layer is desired to be as thin as possible. For example, consider a silicon solar cell in which an n layer is formed on a p-type silicon substrate as shown in FIG.

  FIG. 23 is a cross-sectional view of a single crystal silicon solar cell 3003 in the solar cell module 3001 according to Comparative Example 2.

  As shown in FIG. 23, the single crystal silicon solar cell 3003 includes an n layer 3003n, an i layer 3003i, and a p layer 3003p in order from the light incident surface.

  When the light L10 is incident on the single crystal silicon solar cell 3003, carriers (electron-holes) are generated in all of the n layer 3003n, the i layer 3003i, and the p layer 3003p. In order to take out the generated carrier as an electric current, the carrier must be carried to the electrode. If the carriers recombine before reaching the electrodes, they cannot be taken out as current.

  Carriers generated in the i layer 3003i are decomposed by an internal electric field and can be efficiently extracted as a current. However, carriers generated in the n-layer 3003n and the p-layer 3003p have no electric field, and are thus transported by carrier diffusion and taken out as current. In the case of majority carriers (holes in the p layer, electrons in the n layer), recombination before reaching the electrode does not significantly affect the current drop, but minority carriers (in the p layer) For example, in the case of electrons and holes in the case of n layers, recombination before reaching the electrode has a large effect on current reduction.

  Accordingly, only carriers located at a distance shorter than the minority carrier diffusion length from the i layer 3003i are transported to the i layer 3003i. In other words, carriers generated from the i layer 3003 i at a location away from the carrier diffusion length cannot be sufficiently extracted as current because of recombination. In the case of the single crystal silicon solar cell 3003, the lower part of the p layer 3003p (for example, the carrier generation region CA2 in FIG. 23) corresponds to this.

  As described above, a general single crystal silicon solar cell 3003 has a laminated structure of a surface electrode 3002, an n layer 3003n, an i layer 3003i, a p layer 3003p, and a back electrode from the sunlight incident surface, and the p The thickness of the layer 3003p is relatively thickest. As shown in FIG. 23, the i layer 3003i exists in a shallow region from the sunlight incident surface.

For example, when the light L10 is incident from the light incident surface, many carriers are generated around a shallow region from the light incident surface, that is, around the i layer 3003i (for example, the carrier generation region CA1 in FIG. 23). As described above, carriers generated in the vicinity of the i layer 3003i can be efficiently extracted as a current.
On the other hand, when the wavelength-converted light from the wavelength converter 3005 is incident on the single crystal silicon solar cell 3003 from the back electrode 3004 side, centering on a shallow region from the light incident surface, that is, the lower part of the p layer 3003p (for example, FIG. 23). Many carriers are generated centering around the carrier generation region CA2). As described above, carriers generated in the lower part of the p layer 3003p cannot be taken out as a current when the “distance between the position where the carrier is generated and the i layer 3003i” is larger than the “carrier diffusion length”.

  The position at which carriers are generated (depth from the incident surface) depends on the wavelength of incident light and cannot be uniquely determined, but is derived from the asymmetry of the stacked structure of the single crystal silicon solar cell 3003. It can be estimated at least that the difference in efficiency occurs between the incident from the front electrode 3002 side and the incident from the back electrode 3004 side.

On the other hand, according to the solar cell module 1 in the present embodiment, the phosphor 21 absorbs the incident light even if light enters from any surface of the light collector 2. The phosphor 21 that has absorbed the incident light emits light, and the emitted light always enters the surface of the solar cell element 3 after being guided through the light collector. Therefore, according to the solar cell module 1 in the present embodiment, the light power conversion efficiency does not change even if light enters from any surface of the light collector 2.
That is, the solar cell module 1 in the present embodiment has a feature that the light power conversion efficiency does not change even if light enters from any surface of the light collector 2 due to the symmetry of the shape and structure.

  As described above, according to the solar cell module 1 of the present embodiment, the light that has passed through the light collector 2 without being absorbed by the phosphor 21 is absorbed by the wavelength converter 7 by the wavelength converter 7. Then, it is converted into light that can be absorbed by the phosphor 21 and emitted. For this reason, the light converted by the wavelength converter 7 is absorbed by the phosphor 21, so that light that has been transmitted through the light guide and has not contributed to power generation can contribute to power generation. Therefore, according to the present embodiment, high power generation efficiency can be obtained.

  Moreover, according to this embodiment, since the wavelength converter 7 is arrange | positioned at the 2nd main surface 2b side of the light-condensing plate 2, the light which permeate | transmitted the light-condensing plate 2 among the light which injected into the light-condensing plate 2 is wavelength. The light can be sufficiently absorbed by the converter 7 and can be converted into light that can be absorbed by the phosphor 21 and emitted.

  If the wavelength converter 7 is disposed inside the light collector 2, the light guide characteristics of the light collector 2 may be degraded. On the other hand, according to the present embodiment, since the wavelength converter 7 is disposed outside the light collector 2 (on the second main surface 2b side), it is avoided that the light guide characteristics of the light collector 2 are deteriorated. can do.

  Moreover, according to this embodiment, since the wavelength converter 7 is arrange | positioned through the air layer 9 in the 2nd main surface 2b side of the light-condensing plate 2, the refractive index of the light-condensing plate 2 and the refraction | bending of the air layer 9 are carried out. The difference in refractive index from the index is large. Therefore, the light propagating through the light collector 2 is likely to be totally reflected at the interface between the light collector 2 and the air layer 9, and light loss can be reduced.

  Moreover, according to this embodiment, since the wavelength converter 7 includes a plurality of particles 70 made of an inorganic wavelength conversion material, light transmitted through the light collector 2 out of light incident on the light collector 2 is transmitted by the particles 70. It can be absorbed sufficiently and can be converted into light that can be absorbed by the phosphor 21 and emitted.

  Further, according to the present embodiment, since the void 71 is formed between the two adjacent particles 70, the light emitted isotropically from the particle 70 is refracted and reflected at the interface between the particle 70 and the void 71. As a result, it has light scattering properties. Therefore, the light emitted isotropically from the particles 70 is scattered and easily extracted upward while traveling through the wavelength converter 7 composed of the peripheral particles 70 and the voids 71. Therefore, the light converted by the wavelength converter 7 so as to be absorbed by the phosphor 21 is easily emitted toward the light collector 2.

  Further, according to the present embodiment, since the reflection plate 8 is disposed on the opposite side of the wavelength converter 7 from the light collector 2 side, the light transmitted through the light collector 2 further passes through the wavelength converter 7. However, even if the light converted to be absorbed by the phosphor 21 by the wavelength converter 7 is directed to the side opposite to the light collector 2, these lights are reflected on the surface of the reflector 8. Accordingly, loss of light can be reduced.

  Further, according to the present embodiment, since the wavelength converter 7 is formed on the surface of the reflector 8 on the side of the light collector 8, even if the light transmitted through the light collector 2 further passes through the wavelength converter 7. Even when the light converted to be absorbed by the phosphor 21 by the wavelength converter 7 is directed to the side opposite to the light collector 2, these lights are reflected on the surface of the reflector 8 immediately after that. Therefore, the loss of light can be reduced more reliably. Further, since the wavelength converter 7 can be formed using the reflector 8 as a substrate, when the wavelength converter 7 includes a plurality of particles 70 made of an inorganic wavelength conversion material, the wavelength converter 7 is separated from the reflector 8. It is easier to manufacture than forming.

  Further, according to the present embodiment, since the wavelength converter 7 scatters at least a part of the light (L1 and L2 in FIG. 10) transmitted through the light collector 2, the light absorbed by the phosphor 21 (FIG. 10). Even if L1) passes through the light collector 2, the transmitted light (visible light) (L1 in FIG. 10) is scattered by the wavelength converter 7 and returned to the light collector 2 again. Accordingly, loss of light can be reduced.

[Second Embodiment]
FIG. 24 is a cross-sectional view showing a solar cell module 201 according to the second embodiment.

  As shown in FIG. 24, the basic configuration of the solar cell module 201 according to this embodiment is the same as that of the first embodiment, and the light collector 202 includes a plurality of types of phosphors (for example, the first phosphor 121 and the phosphor in this embodiment). The second embodiment is different from the first embodiment in that the second phosphor 122 includes two kinds of phosphors). Therefore, in this embodiment, description of the basic composition of the solar cell module 201 is abbreviate | omitted.

  In the case of the present embodiment, two types of phosphors, the first phosphor 121 and the second phosphor 122, are dispersed inside the light collector 202. The first phosphor 121 absorbs blue to green light and emits green fluorescence. The second phosphor 122 absorbs green to orange light and emits orange fluorescence. In the present embodiment, BASF Lumogen F Green (trade name) is used as the first phosphor 121, and BASF Lumogen F Orange (trade name) is used as the second phosphor 122. The first phosphor 121 absorbs light having a wavelength of approximately 400 nm to 500 nm. The emission spectrum of the first phosphor 121 has a peak wavelength at 490 nm. The second phosphor 122 absorbs light having a wavelength of approximately 450 nm to 550 nm. The emission spectrum of the second phosphor 122 has a peak wavelength at 540 nm.

  The two types of phosphors 121 and 122 have different absorption spectrum peak wavelengths. The peak wavelength of the spectrum of at least one of the two types of phosphors 121 and 122 and the peak wavelength of the emission spectrum of the wavelength converter 7 are substantially the same. For example, the peak wavelength of the absorption spectrum of the phosphor 121 and the peak wavelength of the emission spectrum of the wavelength converter 7 are generally matched. Here, “substantially match” is defined as follows.

The term “substantially matches” means that the peak wavelength of the emission spectrum of the wavelength converter 7 is included in the “first wavelength range” shown below.
The “first wavelength range” is “the absorbance (or absorbance) of the phosphor 121 is 0 when the absorbance (or absorbance) at the peak wavelength of the absorption spectrum of the phosphor 121 is 1 in the wavelength range of 300 nm to 1000 nm. .Wavelength range that is greater than or equal to 1. "

  For example, in the case of FIG. 12, the “first wavelength range” is 0.1λ1 ≦ λ ≦ 0.1λ2. Here, the peak wavelength λp of the absorption spectrum of the phosphor is a wavelength at which the absorbance of the phosphor 121 is maximum in the wavelength range of 300 nm to 1000 nm. Since the “first wavelength range” is the absorption band of the phosphor 121, it is possible to absorb the light emitted from the wavelength converter 7.

Moreover, it is more preferable that the peak wavelength of the emission spectrum of the wavelength converter 7 is included in the “second wavelength range” shown below.
The “second wavelength range” is “the absorbance (or absorbance) of the phosphor 121 is 0 when the absorbance (or absorbance) at the peak wavelength of the absorption spectrum of the phosphor 121 is 1 in the wavelength range of 300 to 1000 nm. Is defined as a wavelength region that is .5 or more.

  For example, in the case of FIG. 12, the “second wavelength range” is 0.5λ1 ≦ λ ≦ 0.5λ2. The “second wavelength range” is the range of the full width at half maximum of the peak wavelength λp of the absorption spectrum of the phosphor, and is in the vicinity of the absorption peak wavelength λp of the phosphor 121. Can be absorbed.

  According to the solar cell module 201 in the present embodiment, the wavelength converter 7 allows the light collector 2 to be absorbed without being absorbed by either the first phosphor 121 or the second phosphor 122 among the light incident on the light collector 2. The transmitted light is absorbed, converted into light that can be absorbed by either the first phosphor 121 or the second phosphor 122, and emitted. Therefore, the light converted by the wavelength converter 7 is absorbed by either the first phosphor 121 or the second phosphor 122, thereby contributing to power generation. Therefore, according to the present embodiment, high power generation efficiency can be obtained.

  In the present embodiment, the case where two types of phosphors are used as the plurality of types of phosphors has been described. However, the present invention is not limited to this, and three or more types of phosphors may be used.

For example, when four types of phosphors are used, Lumogen F Green (trade name) manufactured by BASF, which is a green light-emitting phosphor, is used as the first phosphor. As the second phosphor, Lumogen F Orange (trade name) manufactured by BASF, which is an orange light emitting phosphor, is used. As the third phosphor, BASF Lumogen F Red (trade name), which is a red light-emitting phosphor, is used. Each density | concentration of 1st fluorescent substance, 2nd fluorescent substance, and 3rd fluorescent substance is 0.02 wt% with respect to the weight of the transparent base material 20 (PMMA resin).
As the fourth phosphor, “Perylene perinone” which is a near-infrared emitting phosphor is used. “Perylene perinone” is described in a non-patent document “APPLIED OPTICS / Vol.50, No. 2/10 January 2011”. The density | concentration of 4th fluorescent substance is 0.005 wt% with respect to the weight of the transparent base material 20 (PMMA resin). The plate thickness of the transparent substrate 20 is 4 mm.
Hereinafter, the case where four types of phosphors are used will be described with reference to FIGS.

First, the spectrum of sunlight (air mass 1.5) will be described with reference to FIG.
FIG. 25 is a diagram showing a spectrum of sunlight (air mass 1.5). In FIG. 25, the horizontal axis represents wavelength [nm] and the vertical axis represents intensity [mW / cm ² / nm].

  As shown in FIG. 25, the spectrum of sunlight (air mass 1.5) has a peak wavelength in the visible wavelength region. The peak wavelength of the sunlight spectrum (air mass 1.5) is approximately 500 nm. The wavelength range of the sunlight spectrum (air mass 1.5) is approximately in the range of 280 nm to 4000 nm.

Next, the absorption characteristics of the four types of phosphors and the absorption characteristics of the light collector will be described with reference to FIGS. 26 and 27. FIG.
FIG. 26 is a diagram showing the absorption spectra of each of the four types of phosphors and the absorption spectrum of the light collecting plate in which the four types of phosphors are mixed. In FIG. 26, the horizontal axis represents wavelength [nm] and the vertical axis represents absorbance [au]. In FIG. 26, “G” is the absorption spectrum of the green light emitting phosphor, “O” is the absorption spectrum of the orange light emitting phosphor, “R” is the absorption spectrum of the red light emitting phosphor, and “NIR” is the near infrared light emitting phosphor. The “Blend” is an absorption spectrum of a light collecting plate in which the above four types of phosphors are mixed.

  As shown in FIG. 26, the four types of phosphors have different absorption spectrum peak wavelengths. The peak wavelength of the absorption spectrum of the green light emitting phosphor is approximately 475 nm. The peak wavelength of the absorption spectrum of the orange light emitting phosphor is approximately 525 nm. The peak wavelength of the absorption spectrum of the red light emitting phosphor is approximately 575 nm. The peak wavelength of the absorption spectrum of the near-infrared emitting phosphor is approximately 625 nm.

  The shape of the absorption spectrum of the light collecting plate in which four kinds of phosphors are mixed is the shape of the absorption spectrum of the green light emitting phosphor, the shape of the absorption spectrum of the orange light emitting phosphor, the shape of the absorption spectrum of the red light emitting phosphor, and the near infrared. The shape covers the shape of the absorption spectrum of the light emitting phosphor.

  FIG. 27 is a diagram showing an absorption spectrum of a light collecting plate in which four types of phosphors are mixed. In FIG. 27, the horizontal axis represents wavelength [nm], and the vertical axis represents absorption rate [%].

  As shown in FIG. 27, the light collecting plate in which four kinds of phosphors are mixed has an absorptance of approximately 100% in a wavelength range of 200 nm to 600 nm. As shown in FIGS. 26 and 27, by dispersing four types of phosphors inside the light collecting plate, a light collecting plate capable of absorbing light in a specific wavelength region can be obtained.

Next, the spectrum of sunlight that passes through a light collector in which four types of phosphors are mixed will be described with reference to FIG.
FIG. 28 shows the spectrum Sq1 of sunlight transmitted through the light collecting plate in which four types of phosphors are mixed, and the transmission spectrum St1 of the light collecting plate in which sunlight spectrum Sp (air mass 1.5) and four types of phosphors are mixed. It is a figure shown with. In FIG. 28, the horizontal axis represents wavelength [nm], the left vertical axis represents intensity [mW / cm 2 / nm], and the right vertical axis represents transmittance [%]. The transmission spectrum St1 includes a surface reflectance of 3.9% as a non-transmission component.

  As shown in FIG. 28, the spectrum Sq1 of sunlight transmitted through the light collecting plate in which four types of phosphors are mixed is obtained by multiplying the spectrum Sp of sunlight and the transmission spectrum St1. The spectrum Sq1 of sunlight transmitted through the light collector mixed with four kinds of phosphors exists in a wavelength range of 600 nm to 4000 nm. In FIG. 28, the range up to 1000 nm is shown for convenience.

Next, emission characteristics and excitation characteristics when NaYF4: Er, Yb is used as the multiphoton excitation phosphor will be described with reference to FIG.
FIG. 29 is a diagram showing an emission spectrum Sr1 and an excitation spectrum Su1 when NaYF4: Er, Yb is used as the multiphoton excitation phosphor. In FIG. 29, the horizontal axis represents wavelength [nm], and the vertical axis represents intensity [au].

  As shown in FIG. 29, the peak wavelength of the emission spectrum Sr1 is approximately 550 nm. The excitation spectrum Su1 exists in a wavelength range of 930 nm to 960 nm. Note that the excitation spectrum Su1 and the absorption spectrum can be regarded as substantially equivalent. This is because it is difficult to directly measure the absorption spectrum when the multiphoton excitation phosphor is a particle made of an inorganic wavelength conversion material.

Next, the relationship between the light emission characteristics when NaYF4: Er, Yb is used as the multiphoton excitation phosphor and the absorption characteristics of the light collecting plate in which four kinds of phosphors are mixed will be described with reference to FIG.
FIG. 30 is a diagram showing the relationship between the emission spectrum Sr1 when NaYF4: Er, Yb is used as the multiphoton excitation phosphor and the absorption spectrum Sa1 of the light collecting plate in which four kinds of phosphors are mixed. In FIG. 30, the horizontal axis is the wavelength [nm], the left vertical axis is the absorption rate [%] of the light collector, and the right vertical axis is the emission intensity [au] of the multiphoton excited phosphor.

  As shown in FIG. 30, the peak wavelength of the emission spectrum Sr1 is approximately 550 nm. The absorption spectrum Sa1 has an absorptance of approximately 100% in the wavelength range of 200 nm to 600 nm. Since the emission spectrum Sr1 of the multiphoton excitation phosphor and the absorption spectrum Sa1 of the light collector overlap, the light emission from the multiphoton excitation phosphor can be sufficiently absorbed by the light collector.

Further, when three types of phosphors are used, Lumogen F Green (trade name) manufactured by BASF, which is a green light emitting phosphor, is used as the first phosphor. As the second phosphor, Lumogen F Orange (trade name) manufactured by BASF, which is an orange light emitting phosphor, is used. As the third phosphor, BASF Lumogen F Red (trade name), which is a red light-emitting phosphor, is used. Each density | concentration of 1st fluorescent substance, 2nd fluorescent substance, and 3rd fluorescent substance is 0.02 wt% with respect to the weight of the transparent base material 20 (PMMA resin).
Hereinafter, the case where three types of phosphors are used will be described with reference to FIGS.

First, the absorption characteristics of the three types of phosphors and the absorption characteristics of the light collector will be described with reference to FIGS. 31 and 32. FIG.
FIG. 31 is a diagram showing the absorption spectrum of each of the three types of phosphors and the absorption spectrum of the light collecting plate in which the three types of phosphors are mixed. In FIG. 31, the horizontal axis represents wavelength [nm] and the vertical axis represents absorbance [au]. In FIG. 31, “G” is the absorption spectrum of the green-emitting phosphor, “O” is the absorption spectrum of the orange-emitting phosphor, “R” is the absorption spectrum of the red-emitting phosphor, and “Blend” is the above three types of phosphors. It is an absorption spectrum of the light collecting plate mixed.

  As shown in FIG. 31, the three types of phosphors have different absorption spectrum peak wavelengths. The peak wavelength of the absorption spectrum of the green light emitting phosphor is approximately 475 nm. The peak wavelength of the absorption spectrum of the orange light emitting phosphor is approximately 525 nm. The peak wavelength of the absorption spectrum of the red light emitting phosphor is approximately 575 nm.

  The shape of the absorption spectrum of the light collecting plate in which the three kinds of phosphors are mixed covers the shape of the absorption spectrum of the green light emitting phosphor, the shape of the absorption spectrum of the orange light emitting phosphor, and the shape of the absorption spectrum of the red light emitting phosphor. It has a shape.

  FIG. 32 is a diagram showing an absorption spectrum of a light collecting plate in which three kinds of phosphors are mixed. In FIG. 32, the horizontal axis represents wavelength [nm], and the vertical axis represents absorption rate [%].

  As shown in FIG. 32, the light collecting plate in which three kinds of phosphors are mixed has an absorptance of approximately 100% in a wavelength range of 200 nm to 540 nm. As shown in FIGS. 31 and 32, by dispersing three types of phosphors inside the light collecting plate, a light collecting plate capable of absorbing light in a specific wavelength region can be obtained.

Next, the spectrum of sunlight that passes through a light collector in which three kinds of phosphors are mixed will be described with reference to FIG.
FIG. 33 shows the spectrum Sq2 of sunlight transmitted through the light collecting plate in which three kinds of phosphors are mixed, and the transmission spectrum St2 of the light collecting plate in which sunlight spectrum Sp (air mass 1.5) and three kinds of phosphors are mixed. It is a figure shown with. In FIG. 33, the horizontal axis represents wavelength [nm], the left vertical axis represents intensity [mW / cm 2 / nm], and the right vertical axis represents transmittance [%]. The transmission spectrum St2 includes a surface reflectance of 3.9% as a non-transmission component.

  As shown in FIG. 33, the spectrum Sq2 of sunlight transmitted through the light collecting plate in which three kinds of phosphors are mixed is obtained by multiplying the spectrum Sp of sunlight and the transmission spectrum St2. The spectrum Sq2 of sunlight that passes through the light collecting plate in which three kinds of phosphors are mixed exists in a wavelength range of 550 nm to 1000 nm.

Next, emission characteristics and excitation characteristics when Gd ₂ (WO ₄ ) ₃ : Tm, Yb is used as the multiphoton excitation phosphor will be described with reference to FIG.
FIG. 34 is a diagram showing an emission spectrum Sr2 and an excitation spectrum Su2 when Gd ₂ (WO ₄ ) ₃ : Tm, Yb is used as the multiphoton excitation phosphor. In FIG. 33, the horizontal axis represents wavelength [nm] and the vertical axis represents intensity [au].

  As shown in FIG. 34, the peak wavelength of the emission spectrum Sr2 is approximately 465 nm. The excitation spectrum Su2 exists in a wavelength range of 950 nm to 1050 nm.

Next, with reference to FIG. 35, the relationship between the emission characteristics when Gd ₂ (WO ₄ ) ₃ : Tm, Yb is used as the multiphoton excitation phosphor and the absorption characteristics of the light collector mixed with three kinds of phosphors is used. explain.
FIG. 35 is a diagram showing a relationship between an emission spectrum Sr2 when Gd ₂ (WO ₄ ) ₃ : Tm, Yb is used as a multiphoton excitation phosphor and an absorption spectrum Sa2 of a light collector plate in which three kinds of phosphors are mixed. It is. In FIG. 35, the horizontal axis is the wavelength [nm], the left vertical axis is the absorption rate [%] of the light collector, and the right vertical axis is the emission intensity [au] of the multiphoton excitation phosphor.

  As shown in FIG. 35, the peak wavelength of the emission spectrum Sr2 is approximately 465 nm. The absorption spectrum Sa2 has an absorptance of approximately 100% in the wavelength range of 200 nm to 540 nm. Since the emission spectrum Sr2 of the multiphoton excitation phosphor and the absorption spectrum Sa2 of the light collector overlap, the light emission from the multiphoton excitation phosphor can be sufficiently absorbed by the light collector.

[Third embodiment]
FIG. 36 is a cross-sectional view showing a solar cell module 301 according to the third embodiment.

  As shown in FIG. 36, the basic configuration of the solar cell module 301 according to this embodiment is the same as that of the first embodiment, and the wavelength converter 307 is included in the light collector 302 in the first embodiment. And different. Therefore, in this embodiment, the description of the basic configuration of the solar cell module 301 is omitted.

  The wavelength converter 307 includes a plurality of particles 370 made of an organic wavelength conversion material. For example, organic wavelength conversion materials are described in non-patent literature `` Journal of Applied Physics, Vol. 81, No. 6, 15 March 1997 '' `` trans-4 @ p- ~ N-hydroxyethyl-N-methylamino! A dye called “stryryl # -N-methylpyridinium iodide” can be used.

According to the solar cell module 301 of this embodiment, the wavelength converter 307 absorbs light that has not been absorbed by the phosphor 21 out of light incident on the light collector 302 and converts it into light that can be absorbed by the phosphor 21. And then injected. Therefore, the light converted by the wavelength converter 307 is absorbed by the phosphor 21 and can contribute to power generation. Therefore, according to the present embodiment, high power generation efficiency can be obtained.
Moreover, since the light converted by the wavelength converter 307 is absorbed by the phosphor 21 inside the light collector 302, the phosphor 21 is excited with high efficiency.

[Fourth embodiment]
FIG. 37 is a cross-sectional view showing a solar cell module 401 according to the fourth embodiment.

  As shown in FIG. 37, the basic configuration of the solar cell module 401 according to this embodiment is the same as that of the third embodiment, and the wavelength converter 407 is included in the light collector 402 together with the wavelength converter 307. Is different from the third embodiment. Therefore, in this embodiment, the description of the basic configuration of the solar cell module 401 is omitted.

The wavelength converter 407 includes a plurality of particles 470 made of an inorganic wavelength conversion material. For example, the inorganic wavelength conversion material is “NaYF ₄ : Yb ³⁺ , Er ³⁺ co-activated nanoparticle phosphor and cyanine dye introduced in non-patent document“ Nature Materials 2012, vol.11, p.842-843 ”. Inorganic-organic hybrid materials modified with (IR-806) can be used.
Moreover, even if it is not an inorganic-organic hybrid material, even if it is an inorganic up-conversion fluorescent substance with a particle size of a nanometer order size, an effect can be acquired by installing in an inside of a light-condensing plate. For example, typical nanoparticle up-conversion phosphors include NaYF ₄ : Yb ³⁺ , Er ³⁺ and NaYF ₄ : Yb ³⁺ , Tm ³⁺ .

  The two types of wavelength converters 307 and 407 have different absorption spectrum peak wavelengths. Of the two types of wavelength converters 307 and 407, the peak wavelength of the emission spectrum of at least one of the wavelength converters and the peak wavelength of the absorption spectrum of the phosphor 21 are substantially the same. For example, the peak wavelength of the absorption spectrum of the phosphor 21 and the peak wavelength of the emission spectrum of the wavelength converter 307 are generally matched. Here, “substantially match” is defined as follows.

“Generally match” means that the peak wavelength of the emission spectrum of the wavelength converter 307 is included in the “first wavelength range” shown below.
The “first wavelength range” is “the absorbance (or absorbance) of the phosphor 21 is 0 when the absorbance (or absorbance) at the peak wavelength of the absorption spectrum of the phosphor 21 is 1 in the wavelength range of 300 nm to 1000 nm. .Wavelength range that is greater than or equal to 1. "

  For example, in the case of FIG. 12, the “first wavelength range” is 0.1λ1 ≦ λ ≦ 0.1λ2. Here, the peak wavelength λp of the absorption spectrum of the phosphor is a wavelength at which the absorbance of the phosphor 21 is maximum in the wavelength range of 300 nm to 1000 nm. Since the “first wavelength range” is the absorption band of the phosphor 21, it is possible to absorb the light emitted from the wavelength converter 307.

Moreover, it is more preferable that the peak wavelength of the emission spectrum of the wavelength converter 307 is included in the “second wavelength range” shown below.
The “second wavelength range” is “in the wavelength range of 300 nm to 1000 nm, where the absorbance (or absorbance) at the peak wavelength of the absorption spectrum of the phosphor 21 is 1, the absorbance (or absorbance) of the phosphor 21 is 0. Is defined as a wavelength region that is .5 or more.

  For example, in the case of FIG. 12, the “second wavelength range” is 0.5λ1 ≦ λ ≦ 0.5λ2. The “second wavelength range” is the range of the full width at half maximum of the peak wavelength λp of the absorption spectrum of the phosphor, and is in the vicinity of the absorption peak wavelength λp of the phosphor 21, so that the wavelength converter 307 emits light more efficiently and sufficiently. Can be absorbed.

According to the solar cell module 401 in the present embodiment, light that has not been absorbed by the phosphor 21 out of light incident on the light collector 402 is absorbed by the wavelength converter 307 and the wavelength converter 407, and is absorbed by the phosphor 21. It is converted into possible light and emitted. For this reason, the light converted by the wavelength converter 307 and the wavelength converter 407 is absorbed by the phosphor 21, thereby contributing to power generation. Therefore, according to the present embodiment, high power generation efficiency can be obtained.
Further, since the light converted by the wavelength converter 307 and the wavelength converter 407 is absorbed by the phosphor 21 inside the light collector 402, the phosphor 21 is excited with high efficiency.

[Fifth Embodiment]
FIG. 38 is a cross-sectional view showing a solar cell module 501 according to the fifth embodiment.

  As shown in FIG. 38, the basic configuration of the solar cell module 501 according to this embodiment is the same as that of the first embodiment, and a support plate 508 that supports the wavelength converter 7 is provided instead of the reflector 8. This is different from the first embodiment. Therefore, in this embodiment, the description of the basic configuration of the solar cell module 501 is omitted.

  For example, the support plate 508 is a back sheet for a general solar cell module. Specifically, it is a sheet in which a PET film is used as a base material and an organic thin film is laminated on the base material. In addition, the thing which has transparency may be sufficient, and the thing which has diffuse reflection property may be sufficient.

  According to the solar cell module 501 in the present embodiment, a high reflectance can be realized even if the reflecting plate 8 is not provided. As shown in FIG. 16, since the wavelength converter 7 has a plurality of interfaces between the particles 70 and the voids 71, even if the light absorbed by the phosphor 21 passes through the light collector 2, This is because most of the transmitted light cannot enter the wavelength converter 7 deeply and is reflected near the surface of the wavelength converter 7.

[Sixth Embodiment]
FIG. 39 is a cross-sectional view showing a solar cell module 601 according to the sixth embodiment.

  As shown in FIG. 39, the basic configuration of the solar cell module 601 according to this embodiment is the same as that of the fifth embodiment, and the reflection plate 8 is provided on the opposite side of the support plate 508 from the wavelength converter 7. This is different from the fifth embodiment. Therefore, in this embodiment, the description of the basic configuration of the solar cell module 601 is omitted.

  According to the solar cell module 601 in the present embodiment, even if the light transmitted through the light collector 2 is further transmitted through the wavelength converter 7 and the support plate 508, the transmitted light is reflected on the surface of the reflective plate 8. Accordingly, loss of light can be reduced.

[Solar power generator]
FIG. 40 is a schematic configuration diagram of the solar power generation device 1000.
The solar power generation apparatus 1000 includes a solar cell module 1001 that converts sunlight energy into electric power, an inverter (DC / AC converter) 1004 that converts DC power output from the solar cell module 1001 into AC power, A storage battery 1005 that stores DC power output from the battery module 1001.

  The solar cell module 1001 includes a light collecting member (light collecting plate) 1002 that collects sunlight, and a solar cell element 1003 that generates power using the sunlight collected by the light collecting member 1002. As such a solar cell module 1001, for example, the solar cell module described in the first to sixth embodiments is preferably used.

The solar power generation device 1000 supplies power to the external electronic device 1006. The electronic device 1006 is supplied with power from the auxiliary power source 1007 as necessary.
Since the solar power generation device 1000 having such a configuration includes the above-described solar cell module according to the present invention, high power generation efficiency can be obtained.

As mentioned above, although preferred embodiment which concerns on this invention was described referring drawings, it cannot be overemphasized that this invention is not limited to said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above embodiment are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.
In addition, specific descriptions regarding the shape, number, arrangement, material, formation method, and the like of each component of the solar cell module are not limited to the above-described embodiment, and can be changed as appropriate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

  The inventor of the present application may refer to how much light energy (hereinafter, also referred to as non-utilized energy) transmitted through the light collector is emitted energy of the wavelength converter (hereinafter referred to as reuse energy). ) Was calculated. Hereinafter, description will be made with reference to FIGS. 41 to 44 and Table 2. FIG.

[Configuration of solar cell module]
(1) PMMA resin (refractive index 1.49) was used for the plate material of the light collector.
(2) As the light collector, one having a side length of about 100 cm and a thickness of about 4 mm was used.
(3) Four types of phosphors, which are organic phosphors, were used as phosphors. As the first phosphor, Lumogen F Green (trade name) manufactured by BASF, which is a green light-emitting phosphor (G), was used. As the second phosphor, Lumogen F Orange (trade name) manufactured by BASF, which is an orange light emitting phosphor (O), was used. As the third phosphor, Lumogen F Red (trade name) manufactured by BASF, which is a red light emitting phosphor (R), was used. The concentration of each of the first phosphor, the second phosphor, and the third phosphor was 0.02 wt% with respect to the weight of the PMMA resin.
As the fourth phosphor, “Perylene perinone” which is a near-infrared light emitting phosphor (IR ₁ ) was used. “Perylene perinone” is described in a non-patent document “APPLIED OPTICS / Vol.50, No. 2/10 January 2011”.
The density | concentration of 4th fluorescent substance was 0.005 wt% with respect to the weight of the transparent base material 20 (PMMA resin).
(4) A GaAs solar cell was used as the solar cell element. The average conversion efficiency of GaAs solar cells is 25%.

[Calculation parameters, etc.]
(1) The solar energy utilization efficiency was 46.2%.
(2) The surface transmittance of the first main surface and the second main surface of the light collector is 96%.
(3) The quantum efficiency of the phosphor was set to 98%.
(4) The transmittance of the transparent base material (PMMA resin) was 93.6%.
(5) The self-absorption and re-emission efficiency of the phosphor was 87.2%.
(6) The confinement efficiency (total reflectance) of the light collector is 74.1%.
From these calculation parameters, the conversion efficiency of the solar cell module was 12.5%.

[Non-use energy]
Of the above calculation parameters, assuming that the solar energy utilization efficiency (46.2%) is K1 and the surface transmittance (96%) is K2, the non-utilization energy Ep [%] is expressed by the following equation (1). The
Ep = (100−K1) × (K2 / 100) × (K2 / 100)
From the above formula (1), the non-use energy was calculated to be 49.6%.

Next, the spectrum of sunlight that passes through a light collector in which five types of phosphors are mixed will be described with reference to FIG.
FIG. 41 shows the spectrum Sq3 of sunlight transmitted through a light collecting plate in which five kinds of phosphors are mixed, and the transmission spectrum St3 of the light collecting plate in which sunlight spectrum Sp (air mass 1.5) and five kinds of phosphors are mixed. It is a figure shown with. In FIG. 41, the horizontal axis represents wavelength [nm], the left vertical axis represents intensity [mW / cm 2 / nm], and the right vertical axis represents transmittance [%]. The transmission spectrum St3 is obtained from the above calculation parameters.

  As shown in FIG. 41, the spectrum Sq3 of sunlight transmitted through the light collecting plate in which five kinds of phosphors are mixed is obtained by multiplying the spectrum Sp of sunlight and the transmission spectrum St3. The spectrum Sq3 of sunlight that passes through a light collecting plate in which five types of phosphors are mixed exists in a wavelength range of 650 nm to 1600 nm. The portion of the spectrum Sq3 of sunlight that passes through the light collecting plate in which five types of phosphors are mixed corresponds to non-use energy.

[Estimation conditions]
(1) The wavelength converter includes a plurality of multiphoton excitation phosphors and is formed by coating on the surface of the reflector on the light condensing plate side (the wavelength converter 7 according to the first embodiment and Equivalent to the reflector 8).
(2) A multiphoton excitation phosphor (product name: PTIR545) manufactured by Phosphor Technology Ltd (UK) was used as the multiphoton excitation phosphor.
(3) The absorptivity of the wavelength converter was 80%.
(4) The quantum efficiency of the wavelength converter was 80%.
(5) The incidence rate of the light emitted from the wavelength converter to the light collector is 94% based on the calculation result with the light tools.

[Estimated results]
Table 2 shows the results of the trial calculation.

As shown in Table 2, when a phosphor produced by Phosphor Technology Ltd (UK) was used as a multiphoton excitation phosphor,
(1) The emission energy (reuse energy) of the wavelength converter was 1.14%.
(2) Increase in conversion efficiency was 0.28%.

Next, emission characteristics and excitation characteristics when a phosphor produced by Phosphor Technology Ltd (UK) is used as the multiphoton excitation phosphor will be described with reference to FIG.
FIG. 42 shows the emission spectrum Sr10, the absorption spectrum Su10, and the absorption energy spectrum Eu10 when a multi-photon excitation phosphor manufactured by Phosphor Technology Ltd (UK) is used, the solar spectrum Sp, and the five types of phosphors. It is a figure shown with sunlight spectrum Sq3 which permeate | transmits the light-condensing plate mixed. In FIG. 42, the horizontal axis represents wavelength [nm], the left vertical axis represents intensity [au], and the right vertical axis represents absorption rate [%].

  As shown in FIG. 42, the peak wavelength of the emission spectrum Sr10 is approximately 550 nm. The absorption spectrum Su10 exists in a wavelength range of 900 nm to 1000 nm. The peak wavelengths of the absorption spectrum Su10 are approximately 950 nm and 980 nm. The absorption energy spectrum Eu10 is obtained by multiplying the sunlight spectrum Sq3 and the absorption spectrum Su10 that are transmitted through a light collecting plate in which five kinds of phosphors are mixed. The portion of the absorption energy spectrum Eu10 corresponds to the absorption energy. The absorbed energy was 1.64%.

Further, as shown in Table 2, when a phosphor activated by Er ³⁺ alone was used as the multiphoton excitation phosphor,
(1) The emission energy (reuse energy) of the wavelength converter was 1.21%.
(2) Increase in conversion efficiency was 0.30%.

Next, emission characteristics and excitation characteristics when a phosphor activated by Er ³⁺ alone is used as the multiphoton excitation phosphor will be described with reference to FIG.
FIG. 43 shows an emission spectrum Sr11, an absorption spectrum Su11, and an absorption energy spectrum Eu11 when a single photon-excited phosphor activated with Er ³⁺ is used, a sunlight spectrum Sp, and five types of phosphors mixed together. It is a figure shown with sunlight spectrum Sq3 which permeate | transmits a light-condensing plate. In FIG. 43, the horizontal axis represents wavelength [nm], the left vertical axis represents intensity [au], and the right vertical axis represents absorption rate [%].

  As shown in FIG. 43, the peak wavelength of the emission spectrum Sr11 is approximately 550 nm. The absorption spectrum Su11 exists in a wavelength range of 780 nm to 840 nm. The peak wavelength of the absorption spectrum Su11 is approximately 810 nm. The absorption energy spectrum Eu11 is obtained by multiplying the sunlight spectrum Sq3 and the absorption spectrum Su11 that are transmitted through a light collecting plate in which five kinds of phosphors are mixed. The portion of the absorption energy spectrum Eu11 corresponds to the absorption energy. The absorbed energy was 2.06%.

Further, as shown in Table 2, when a multiphoton excitation phosphor co-activated with Yb ³⁺ and Er ³⁺ is used,
(1) The emission energy (reuse energy) of the wavelength converter was 1.05%.
(2) Increase in conversion efficiency was 0.26%.

Next, emission characteristics and excitation characteristics when using Yb ³⁺ and Er ³⁺ co-activated phosphors as multiphoton excitation phosphors will be described with reference to FIG.
44 shows an emission spectrum Sr12, an absorption spectrum Su12, and an absorption energy spectrum Eu12 when a multi-photon excitation phosphor co-activated with Yb ³⁺ and Er ³⁺ is used, a solar spectrum Sp, and five types of phosphors. It is a figure shown with sunlight spectrum Sq3 which permeate | transmits the light-condensing plate mixed. In FIG. 44, the horizontal axis represents wavelength [nm], the left vertical axis represents intensity [au], and the right vertical axis represents absorption rate [%].

  As shown in FIG. 44, the peak wavelength of the emission spectrum Sr12 is approximately 550 nm. The absorption spectrum Su12 exists in a wavelength range of 1000 nm to 1060 nm. The peak wavelength of the absorption spectrum Su12 is approximately 1030 nm. The absorption energy spectrum Eu12 is obtained by multiplying the sunlight spectrum Sq3 and the absorption spectrum Su12 that are transmitted through the light collector in which five kinds of phosphors are mixed. The portion of the absorption energy spectrum Eu12 corresponds to the absorption energy. The absorbed energy was 1.41%.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

  This inventor confirmed the effect of the solar cell module of this invention. Hereinafter, the confirmation result will be described with reference to Table 3.

[Configuration of solar cell module]
(1) PMMA resin (refractive index 1.49) was used for the plate material of the light collector.
(2) As the light collector, one having a side length of about 100 cm and a thickness of about 4 mm was used.
(3) Three types of phosphors, configuration 1 to configuration 3, were used.
(I) Configuration 1 used four types of phosphors.
As the first phosphor, BASF Lumogen F Green (trade name), which is a green light-emitting phosphor, was used. As the second phosphor, Lumogen F Orange (trade name) manufactured by BASF, which is an orange light emitting phosphor, was used. As the third phosphor, BASF Lumogen F Red (trade name), which is a red light-emitting phosphor, was used. The concentration of each of the first phosphor, the second phosphor, and the third phosphor was 0.02 wt% with respect to the weight of the PMMA resin.
As the fourth phosphor, “Perylene perinone”, which is a near-infrared emitting phosphor, was used. “Perylene perinone” is described in a non-patent document “APPLIED OPTICS / Vol.50, No. 2/10 January 2011”. The concentration of the fourth phosphor was 0.005 wt% with respect to the weight of the PMMA resin.
(II) Configuration 2 used three types of phosphors.
As the first phosphor, BASF Lumogen F Green (trade name), which is a green light-emitting phosphor, was used. As the second phosphor, Lumogen F Orange (trade name) manufactured by BASF, which is an orange light emitting phosphor, was used. As the third phosphor, BASF Lumogen F Red (trade name), which is a red light-emitting phosphor, was used. The concentration of each of the first phosphor, the second phosphor, and the third phosphor was 0.02 wt% with respect to the weight of the PMMA resin.
(III) In Configuration 3, the same four types of phosphors as in Configuration 1 were used.

[Comparative example]
The solar cell module used was not provided with a wavelength converter and a reflector. The solar cell module corresponds to the solar cell module 2001 shown in FIG.
[Comparative Example 1]
The phosphor was configured as 1.
[Comparative Example 2]
The phosphor was configured as 2.
[Comparative Example 1]
The phosphor was configured as 3.

[Example]
The solar cell module used was provided with a wavelength converter and a reflector. The solar cell module corresponds to the solar cell module 1 shown in FIG. ESR was used as the reflector.

[Example 1]
The phosphor was configured as 1.
NaYF ₄ : Er, Yb was used as the wavelength converter.
[Example 2]
The phosphor was configured as 2.
Gd ₂ (WO ₄ ) ₃ : Tm, Yb was used as the wavelength converter.
[Example 3]
The phosphor was configured as 3.
As the wavelength converter, a mixture of (1) NaYF ₄ : Er, Yb and (2) Gd ₂ (WO ₄ ) ₃ : Tm, Yb was used.

For each comparative example and each example, 1 Sun (100 mW / cm ² ) of sunlight was vertically incident on the solar cell module, and power generation [W] and conversion efficiency [%] were determined. The results are shown in Table 3.

As shown in Table 3, in “Comparative Example 1”, the power generation amount was 96 [W], and the conversion efficiency was 9.6 [%]. On the other hand, in “Example 1”, the power generation amount was 98.3 [W] (up 2.3 W), and the conversion efficiency was 9.8 [%] (up 0.2%).
In “Comparative Example 2”, the power generation amount was 73.3 [W], and the conversion efficiency was 7.3 [%]. On the other hand, in “Example 2”, the power generation amount was 77.8 [W] (up 4.5 W), and the conversion efficiency was 7.8 [%] (up 0.5%).
In “Comparative Example 3”, the power generation amount was 96 [W], and the conversion efficiency was 9.6 [%]. On the other hand, in “Example 3”, the power generation amount was 102.6 [W] (6.6 W increase), and the conversion efficiency was 10.3 [%] (0.7% increase).

  From the results of each comparative example and each example, it was found that the power generation amount and the conversion efficiency can be increased by providing the wavelength converter and the reflector.

  (1) having a light incident surface and a light exit surface having an area smaller than that of the light incident surface, and absorbing a part of external light incident from the light incident surface by one or a plurality of optical functional materials; A light collector that converts light that is different from the light absorbed by the one or more optical functional materials and emits the light from the light exit surface, and a solar cell that receives the light emitted from the light exit surface of the light collector Light that has not been absorbed by any of the one or more optical functional materials among the light incident on the element and the light incident surface, and is absorbed by any of the one or more optical functional materials A solar cell module including:

  (2) The solar cell module according to (1), wherein the wavelength converter is disposed on a surface of the light collector opposite to the light incident surface.

  (3) The solar cell module according to (2), wherein the wavelength converter is disposed on an opposite surface of the light collector to the light incident surface via an air layer.

  (4) The solar cell module according to (2) or (3), wherein the wavelength converter includes a plurality of particles made of an inorganic wavelength conversion material.

  (5) The solar cell module according to (4), wherein a gap is formed between two adjacent particles.

  (6) The solar cell module according to any one of (2) to (5), wherein a reflection plate is disposed on a side opposite to the light collector of the wavelength converter.

  (7) The said wavelength converter is a solar cell module as described in said (6) currently formed in the surface at the side of the said light-condensing plate of the said reflecting plate.

  (8) The wavelength conversion body according to any one of (2) to (7), wherein the wavelength converter scatters at least a part of light that has passed through the light collector, among light incident on the light incident surface. Solar cell module.

  (9) The solar cell module according to (1), wherein the wavelength converter is included in the light collector.

  (10) The solar cell module according to (9), wherein at least a part of the wavelength converter includes a plurality of particles made of an organic wavelength conversion material.

  (11) The solar cell module according to (9) or (10), wherein at least a part of the wavelength converter includes a plurality of particles made of an inorganic wavelength conversion material.

  (12) In the solar cell module according to any one of (1) to (11), the peak wavelength of the absorption spectrum of any one or the plurality of optical functional materials and the emission spectrum of the wavelength converter. The peak wavelength may substantially match.

  (13) The plurality of optical functional materials are different types of optical functional materials, and a peak wavelength of an absorption spectrum of at least one optical functional material among the plurality of types of optical functional materials and light emission of the wavelength converter. The solar cell module according to (12), wherein a peak wavelength of the spectrum is approximately the same.

  (14) The wavelength converter is a plurality of different wavelength converters, and a peak wavelength of an emission spectrum of at least one of the plurality of wavelength converters and the one or more optical functional materials. The solar cell module according to the above (12) or (13), wherein the peak wavelength of any of the absorption spectra generally coincides.

  (15) The wavelength converter is configured so that at least a part of the light that is not absorbed by any of the one or more optical functional materials is more than the light that is not absorbed by any of the one or more optical functional materials. The solar cell module according to any one of (1) to (14), wherein the light is also converted into light having a short wavelength.

  (16) In the above (15), the wavelength range of light absorbed by any one of the wavelength converters is longer than the wavelength range of light absorbed by any one of the one or more optical functional materials. The solar cell module described.

  (17) The wavelength converter has an emission center that interacts with light that is not absorbed by any of the one or more optical functional materials, and the emission center is between the ground state and the 1 Or the solar cell module as described in said (16) which has a 1st excitation state with the energy gap below the energy which the light which was not absorbed by any of several optical functional materials has.

  (18) The emission center has a second excited state having an energy gap higher than an energy of light not absorbed by any of the one or more optical functional materials between the emission state and the ground state. (17) The solar cell module described in.

  (19) The solar cell module according to (18), wherein electronic transition between the first excited state and a ground state is forbidden.

  (20) The solar cell module according to (19), wherein the emission center includes an element having open-shell f electrons.

  (21) The solar cell module according to (20), wherein the element is a rare earth element.

  (22) The solar cell module according to (20) or (21), wherein the element is Er (erbium), Tm (thulium), or Ho (holmium).

  (23) The solar cell module according to any one of (16) to (22), wherein the wavelength converter includes a sensitizer.

  (24) The solar cell module according to (23), wherein the sensitizer is Yb (ytterbium).

  (25) A solar power generation device including the solar cell module according to any one of (1) to (24).

  The present invention can be used for a solar cell module and a solar power generation device.

DESCRIPTION OF SYMBOLS 1,101,201,301,401,501,601 ... Solar cell module, 2, 202, 302 ... Light-condensing plate, 2a ... 1st main surface (light incident surface), 2c ... End surface (light emission surface), 3 ... Solar cell element, 7,207,307,407 ... wavelength converter, 8 ... reflector, 9 ... air layer, 21 ... phosphor (optical functional material), 70, 370, 470 ... particles, 71 ... void, 1000 ... Solar power plant

Claims (5)

A light incident surface and a light exit surface having a smaller area than the light incident surface, and a part of the external light incident from the light incident surface is absorbed by one or more optical functional materials, A light collector for converting the light absorbed by the plurality of optical functional materials into light different from the light and emitting the light from the light exit surface;
A solar cell element that receives light emitted from the light exit surface of the light collector;
Absorbing light that has not been absorbed by any of the one or more optical functional materials out of light incident on the light incident surface, and converts the light to light absorbed by any of the one or plural optical functional materials. A wavelength converter to be emitted
Including solar cell module.   2. The solar cell module according to claim 1, wherein the wavelength converter is disposed on a surface of the light collector opposite to the light incident surface.   3. The solar cell module according to claim 2, wherein the wavelength converter is disposed on an opposite surface of the light collector from the light incident surface via an air layer.   The solar cell module according to claim 2 or 3, wherein the wavelength converter includes a plurality of particles made of an inorganic wavelength conversion material. The sun according to any one of claims 1 to 4, wherein a peak wavelength of an absorption spectrum of any one or the plurality of optical functional materials and a peak wavelength of an emission spectrum of the wavelength converter are substantially the same. Battery module.

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